Multielement conductive faceplate

ABSTRACT

A METHOD OF CONSTRUCTING A FACEPLATE IS DESCRIBED, WHICH CONTAINS A MULTITUDE OF CLOSELY SPACED, DISCRETE, CONDUCTIVE ELEMENTS TO PERMIT PASSAGE OF ELECTRICAL SIGNALS FROM ONE SIDE OF THE FACEPLATE TO THE OTHER. THE FACEPLATE IS COMPLETELY IMPERMEABLE TO GASES. THIS METHOD COMPRISES PLACING A METAL BAR PATTERN ON RIBBON GLASS, CUTTING AND STACKING SHEETS OF THE GLASS, AND SUBJECTING THE STACK TO HEAT AND PRESSURE. THE METHOD OF CONSTRUCTION PERMITS THE READY PLACEMENT OF A LARGE NUMBER OF CLOSELY SPACED DISCRETE CONDUCTING PATHS TRANSVERSELY THROUGH THE FACEPLATE MAKING POSSIBLE TWO-DIMENSIONAL ARRAYS OF 500 OR MORE ELEMENTS PER INCH.

Oct. 17, 1972 R. E. CURRAN L MULTIELEMENT CONDUCTIVE FACEPLATE Continuous pattern of n metal bars on glass ribbon.

s m 2 Q Filed Dec. 9, 1970 Robert E. Curran,

Richard D. Kefchpel, Glenn D. Roberrson,Jr.,

INVENTORS.

ATTORNEY.

Patented Oct. 17, 1972 3,698,884 MULTIELEMENT CONDUCTIVE FACEPLATE Robert E. Curran, Hawthorne, Glenn D. Robertson, Jr., Malibu, and Richard D. Ketchpel, Santa Barbara, Calif., assignors to Hughes Aircraft Company, Culver City,

Calif.

Filed Dec. 9, 1970, Ser. No. 96,392 Int. Cl. C03]: 29/00; C03c 27/00, 29/00 US. CI. 6543 2 Claims ABSTRACT OF THE DISCLOSURE A method of constructing a faceplate is described, which contains a multitude of closely spaced, discrete, conductive elements to permit passage of electrical signals from one side of the faceplate to the other. The faceplate is completely impermeable to gases. This method comprises placing a metal bar pattern on ribbon glass, cutting and stacking sheets of the glass, and subjecting the stack to heat and pressure. The method of construction permits the ready placement of a large number of closely spaced discrete conducting paths transversely through the faceplate making possible two-dimensional arrays of 500 or more elements per inch.

BACKGROUND OF THE INVENTION Multielement conductive faceplates are presently available, consisting of an array of 0.0005 inch diameter tungsten Wires embedded in a uranium glass spaced in a pseudo-regular pattern approximately 0.004 inch apart. The shortcomings of these faceplates are the small overall size, the high cost and a maximum practical resolution of approximately 325 elements per inch. Faceplates of this type can be fabricated by coating the wires with a sheath of glass cutting the coated wire to length, stacking the individual glass-enclosed wire segments, and fusing the stack together. Faceplates of higher resolution can be fabricated by this technique but the cost increases rapidly as the number of elements per inch is increased.

SUMMARY OF THE INVENTION In accordance with the present invention, a bar pattern is produced on one or both sides of a continuous ribbon of glass; the glass ribbon cut to conform to a linear dimen sion of a faceplate; the ribbon segments stacked, the ribbon with bars on one side being stacked with the bars on a consistent side and ribbon with bars on both sides being interleaved with blank ribbon; heat and pressure are applied to the ribbon stack while immersed in an inert atmosphere thereby to fuse the ribbon segments into one piece.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a continuous strip of glass ribbon with the metal bars being placed on one or both sides thereof;

FIG. 2 illustrates an exploded view of a stack of glass ribbon segments with metal bars on one side thereof;

FIG. 3 illustrates an exploded view of a stack of glass ribbon segments with metal bars on both sides, with blank ribbon segments interleaved therebetween;

FIG. 4 illustrates a cross-sectional View of a stack of glass ribbon segments in FIG. 2 or 3 being fused together in an oven; and

FIG. 5 shows a front view of a finished faceplate.

Referring now to FIG. 1 of the drawings, there is shown a portion of a continuous strip of glass ribbon on which is deposited a transverse metal bar pattern 12. Potash lead glass having a softening point of 525 C. with a width of about 0.5 inch and a thickness of 0.0018 inch, may be utilized to provide the continuous strip of glass ribbon 10. The metal of the metal bar pattern 12 should be relatively non-reactive, such as, for example, chromium, gold, or platinum. The bar pattern 12 comprises electrically isolated strips 13 running across the width of the ribbon normal to the continuous length direction and located on 0.001 inch centers. The bar pattern 12 may be on one side of the glass ribbon 10 only, as shown in FIGS. 1 and 2, or alternatively, may be on both sides of the glass ribbon 10, as shown and discussed in connection with FIG. 3. The thickness of the metal of the individual metal strips 13 of metal bar pattern 12 should preferably exceed 2000 angstroms and the width of the individual strips 13 should be 0.0001 inch or more, provided that adjacent strips 13 are electrically isolated by a DC. resistance of the order of 1000 ohms or more.

There are many ways in which the metal bar pattern 12 can be placed on the glass ribbon 10. A pattern 12 of conductors 13 may, for example, be applied to the glass ribbon 10 by vacuum evaporation. Another method is to use a continuous process wherein the glass ribbon 10 is passed under an electron beam which writes finely spaced parallel lines on the ribbon 10. The ribbon 10 may or may not require sensitization prior to this beam writing step. The exposed ribbon is then developed by a condensing metal vapor as done in the video tape recording system art. If additional metal is required for the respective conducting elements 13, the glass ribbon 10 can be submerged in an electroless plating bath for the desired length of time. The ribbon 10 can then be washed, dried, and rerolled for subsequent use in the same manner as movie film is processed. An alternate method is to coat one side of the glass ribbon 10 with photoresist material, exposing the resist to a bar pattern and developing the bar pattern in the photoresist film to form a pattern of bars. Metal to form the conductive elements is then evaporated or sputtered over the pattern of photoresist bars and a solvent is then used to remove the resist bars and the metal which covers them, leaving a pattern of metal bars firmly bonded to the glass ribbon 10.

To form faceplates, segments of measured length determined by the dimensions of the faceplate to be formed are cut from the roll of glass ribbon 10 and stacked as shown in FIGS. 2 and 3. In FIG. 2, glass ribbon 10 having a metal bar pattern 12 on only one side is used exclusively to provide segments 14, 15, 16, 17 which form a stack 18. In FIG. 3, on the other hand, glass ribbon 10 having a metal bar pattern 12 on both sides is used, in which case segments 19, 20 of plain glass ribbon 10 is interleaved between the segments 21, 22 of glass ribbon having a bar pattern 12 on both sides thereof, to form a stack 23. In actual practice, the segments 1417 and 19-22 conform to exceed the length of the faceplate to be formed and are used in sulficient numbers to provide the width thereof.

To form faceplates, the stack 18 or 23 of FIGS. 2 and 3, respectively, is placed in a mold 25, FIG. 4, composed of, for example, carbon or steel with carbon inserts 26 placed above and below to maintain the stack 18 or 23 under pressure. The mold 25 is then placed in an oven 27 and heated to a temperature above the annealing point of the glass ribbon 10 by means of a thermal element 28. The glass ribbon 10, when of the type hereinbefore specified, is composed of a lead-potash glass which was found to fuse satisfactorily when held at a temperature of 580 C. for 35 minutes in an inert atmosphere such as nitrogen. The carbon inserts 26 are used to transmit a small force during this fusing operation to obtain proper consolidation of the glass ribbons. The completed faceplate 30, FIG. 5, is then polished by conventional means to reveal the metal stripes 13. Thus, the principle of combining metalized glass ribbon into a faceplate has been demonstrated.

What is claimed is:

1. A method of fabricating a faceplate from glass ribbon having an array of electrically discrete conductors disposed therethrough, said method comprising the steps of placing a metal bar pattern transversely across and on at least one side of said glass ribbon;

cutting said glass ribbon into segments having a length no less than a dimension of said faceplate;

stacking said segments coextensively over each other into a mold with said respective metal bar patterns in insulative relationship to each other to form an unconsolidated faceplate;

maintaining said unconsolidated faceplate under pressure; and

heating said mold containing said unconsolidated faceplate in an inert atmosphere to fuse said segments of glass ribbon together thereby to consolidate said faceplate.

2. The method of fabricating a faceplate from glass ribbon having an array of electrically discrete conductors disposed therethrough as defined in claim 1, additionally including the step of polishing said consolidated faceplate to reveal extremities of said transverse metal bar pattern.

References Cited UNITED STATES PATENTS 3,241,934 3/1966 Graritsas et al 6532 3,118,788 1/ 1964 Hensler 65-32 3,310,392 3/1967 Rhodes 6532 3,305,334 2/1967 Fyler 6555 S. LEON BASHORE, Primary Examiner 15 K. M. SCHOR, Assistant Examiner US. Cl. X.R. 

